56
Operation
4.17.4 Electrolytes
When the electrode is with liquid electrolyte the electrolyte level must be controlled and
the electrode should be refilled periodically. The reference electrolyte is used to refill the
storage protector of the membrane too.
KCL-3M solution
This electrolyte is suitable for electrodes which reference element is encapsulated AgCl
crystals.
KCL-3M GLYCERINE.
This is KCl solution in which part of the water is replaced by glycerine. The high glycerine
content prevents a reaction between the KCl and the proteins into the medium. This
prevents early blockage of the diaphragm, extends the life of the electrode and above all
ensures that the electrode operates correctly. Applications: Samples with high protein
content, partially organic, containing oils, at low temperature, etc.
4.17.5 Standard conductivity solutions
Conductivity standards are prepared in line with ASTM D1125-95 and contrasted with
standard reference material (SRM) from the National Institute of Standards & Technology,
NIST. Four standards solutions are available: values at 25ºC of 147 µS/cm, 1413 µS/cm,
12.88 mS/cm and 80.4 mS/cm. Each solution is supplied with a Certificate of Analysis
indicating data relating to nominal value, uncertainty, traceability, composition, batch
number and expiry date.
Values stored in the memory of the MultiMeter 44.
Table 4 Conductivity values according to temperature
°C µS/cm µS/cm mS/cm mS/cm
15.0 119 1147 10.48 66.5
16.0 122 1173 10.72 68.3
17.0 125 1199 10.95 69.1
18.0 127 1225 11.19 70.4
19.0 130 1251 11.43 71.8
20.0 133 1278 11.67 73.1
21.0 136 1305 11.91 74.6
22.0 139 1332 12.15 76.0
23.0 142 1359 12.39 77.4
24.0 145 1386 12.64 78.9
25.0 147 1413 12.88 80.4
26.0 150 1440 13.13 81.7
27.0 153 1467 13.37 83.1
28.0 156 1494 13.62 —
29.0 159 1522 13.87 —
30.0 162 1549 14.12 —
31.0 165 1581 14.37 —
32.0 168 1609 14.62 —
33.0 171 1638 14.88 —
34.0 174 1667 15.13 —
35.0 177 1696 15.39 —
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